An elevated rate of glycolysis has long been known to characterize many types of tumors, but the molecular mechanism(s) by which this change occurs and the possible role of increased glycolysis in tumorigenesis are still poorly understood. Cells transformed by Rous sarcoma virus (RSV) transport glucose and glycolyze at an elevated rate. RSV-transformed cells present a very favorable system for studying the increased glycolytic metabolism because of the availability of well-matched normal and malignant cells, the existence of temperature-conditional and "partial" transformation mutants of RSV, and because of recent advances in understanding the mechanism of RSV-induced transformation. Our research is aimed at elucidating the molecular mechanism and biological significance of the increased glucose metabolism seen in RSV-transformed cells. We have found that increases in hexose transport precede increases in at least some of the glycolytic enzymes during the process of transformation. This indicates that the increased transport rate is closer to the primary events in oncogenesis than the changes in metabolic enzymes. Current research is focusing on analyzing the molecular mechanism by which pp60src alters the level of glucose transporter proteins. (B)